Temperature compensating system for hydropneumatic equilibrator



May 8, 1962 D. E. WITKIN TEMPERATURE COMPENSATING SYSTEM FOR HYDROPNEUMATIC EQUILIBRATOR Filed Jan. 28, 1959 INVENTOR. D m-1&1 E. Mirkin a. a. a m fm MM 3,033,085 TEMPERATURE COMPENSATlNG SYSTEM F HY DROPNEUMATIC EQUILIBRATOR Donald E. Witkin, Levittown, Pa., assignor to the United States of America as represented by the Secretary of the Army Filed Jan. 28, 1959, Ser. No. 789,760 3 Claims. (CI. 8937) This invention relates to a temperature compensating system for a hydropneumatic equilibrator system and more specifically to such a system as applied to guns.

In larger caliber guns in which the gun is adjustable in elevation it is necessary to provide a device for counterbalancing the offset weight of the tipping parts of the gun. An equilibrator is a device for eflecting this compensation. With such a compensation the vweight is balanced on the gun mounting trunnion and the loads on the elevating mechanism are minimized.

An equilibrator system now in use is provided with a tank carrying compressed gas and a limited quantity of hydraulic fluid. A cylinder is carried on the gun mount and carries a slidable piston which is connected to the tipping portion of the gun. The cylinder on one side of the piston is filled with hydraulic fluid and connected to the tank below the liquid level. The gas pressure in the tank acts through the liquid column and piston to provide a compensating force for the gun tipping par-ts. It will be seen that for changes in ambient temperature the gas pressure in the tank will vary and provide overor undercompensation. pensates for temperature changes by means of a complex hydraulic motor and pump system which varies the gas pressure by changing the volume of oil in the system. This system is limited by timeof operation, complexity and the undesirable change in equilibrator performance, i.e., change in balancing force versus elevation relationship for varyingtemperature.

My invention relates to athydropneumatic equilibrator system utilizing a compressed gas tank and piston and cylinder arrangement as described above. However, a greatly simplified temperature compensating means is employed. A second tank is employed and charged with gas under pressure. This tank is connected to the first tank through an on-oif valve. This system permits transfer of gas from one tank to the other when necessary to compensate for temperature changes by using the equilibrator piston and cylinder as a transfer pump.

An object of the invention is to provide a gun equilibratorof the hydropneumatic type provided with temperature compensating means.

Another object of the invention is to provide a gun having a temperature compensating equilibrator in which the power required for temperature compensation is derived from the gun elevating mechanism.

Another object is to provide a gun having a temperature compensated equilibrator of greatly simplified form.

These and other objects will become more apparent when reference is had to the following detailed description and drawing in which:

FIGURE 1 is a schematic view showing the relationship between the equilibrator and gun, and

FIGURE 2 is a schematic view showing the equilibrator and temperature compensating system.

Referring now to the drawing and particularly FIG- URE 1 there is shown schematically a gun having the supporting structure 1 and barrel 2 pivoted to the support by means of the trunnion 3. The elevation of the gun barrel may be changed by any conventional tipping mechanism. The center of gravity of the gun barrel 2 and the parts that move therewith when the gun is elevated is indicated at 0.6. in FIGURE 1 and as shown is forward nited States atent The system now in use comof the trunnion 3. It will be noted that in the absence of a compensating means the unbalanced weight of the barrel would impose additional load on the tipping mechanism, the additional load being greatest when the barrel is horizontal and the center of gravity is furthest from the trunnion and least when the barrel is at maximum elevation and the center of gravity is closest to the trunnion. In order to relieve this additional load on the tipping mechanism a compensating means or equilibrator generally indicated at 4 is provided. This compensating means includes a cylinder 5 pivoted to the support 1 and piston rod 6 pivoted to the gun barrel. A fluid supply system is generally indicated at 7 and is connected to the cylinder 5 by the conduit 8.

Referring now to FIGURE 2 the equilibrator system is shown in more detail. The cylinder 5 slidably carries the piston 9 to which is connected the piston rod 6. The lower end of the cylinder is vented at 10 to atmosphere. An accumulator tank 11 is provided and is connected by means of conduit 8 to the upper end of the cylinder 5. A limited quantity of hydraulic fluid is supplied to the system and fills the upper end of cylinder 5, the conduit 8 and the lower portion of tank 11. Gas under pressure is charged into the upper portion of accumulator tank 11.

It will now be seen that with the system thus far described compensation for the offset barrel weight may be obtained for one given ambient temperature. The size of the accumulator tank is chosen so as to give the necessary volume of compressed gas to correctly compensate for the particular design parameters of the gun. When the barrel is in the lowermost position, i.e. the position in which most compensation is required, the piston 9 is in its uppermost position and the gas in accumulator 11 is most highly compressed. This provides maximum compensating force on the piston rod 6. Conversely, when the gun is at its highest elevation, i.e. the position in which least compensation is required, the piston 9 is in its lowermost position and the gas in accumulator :11 is expanded providing a lower compensating force. If the ambient temperature increases, the gas pressure in tank 11 increases and the gun becomes muzzle light. If the ambient temperature decreases, the gas pressure in tank 11 decreases and the gun becomes muzzle heavy.

The manner in which I compensate for any ambient temperature changes will now be described. Connected to the accumulator tank 11 by means of conduit 12 is the compensator tank 13 which is charged with compressed gas at about the average pressure which exists in the accumulator tank 11 at some arbitrary filling temperature. A shut-off valve 14 is provided in the conduit between the tanks and a pressure gage 15 is connected to the accumulator 11. During normal operation this valve is closed. If the ambient temperature rises it is necessary to decrease the volume of gas in the accumulator 11 to compensate for the temperature change. Under these conditions the gun barrel is moved to its lowest elevation creating a pressure in accumulator tank 11 which is higher than the gas pressure in compensator tank 13. The valve 14 is opened to permit some of the gas in tank 11 to flow to tank 13 and then closed again when the proper pressure has been obtained as indicated by the gage 15. When the ambient temperature decreases it is necessary to in-' crease the pressure in tank 11. In this case the gun is elevated until the pressure in tank 13 exceeds the pressure in accumulator 11. The valve 14 is then opened permitting gas to flow from tank 13 to tank 11 and then closed again.

An inherent property of the system is the fact that for a given set of initial conditions there is a unique position of elevation at which the equilibrator will be properly compensated for temperature when the valve 14 between the compensator and accumulator tanks is opened for any deviation from the initial temperature. The pressure gage can be calibrated in such a manner as to indicate the angle of elevation at which the gun is properly equilibrated for a given temperature. Then the operator can use the compensating system by merely opening the valve 14 and raising or depressing the gun until the reading on the pressure gage corresponds to the actual elevation as read from a mechanical indicator. The valve may then be closed and the system will be compensated for temperature.

The usable temperature range of this system is determined solely by the relative size of the compensator tank 13 and the clearance volume in the accumulator tank 11. Any reasonable range can be obtained by adjusting these volumes accordingly.

It will be seen that -I have devised a temperature compensating system for an equilibrator with a minimum number of moving parts. The only additional parts are the compensating tank and valve and no motors, pumps and complex controls are needed. A separate source of power is not required, the gun elevating mechanism being used to vary the accumulator gas charge. The system also provides the storage of a limited amount of make up gas for equilibrator leakage. Also with this system temperature compensation is accomplished with negligible effect on equilibratoiforce versus elevation angle relationship.

It will be apparent that the embodiment shown is only exemplary and that various modifications can be made in construction and arrangement within'the scope of the invention as defined in the appended claims.

I claim:

1. In combinationwith a gun having a support and barrel mechanism pivoted thereto for movement in elevation, an equilibrator comprising a slidably connected piston and cylinder connected between said support and barrel mechanism, an accumulator tank charged with gas under pressure connected to said cylinder on one side of said piston the gas pressure in said accumulator being highest when the gun in the lowest elevation and lowest when the gun is in highest elevation, means to compensate said equilibrator for changes in ambient temperature comprising a compensating tank charged with gas to a pressure substantially equal to the average pressure in said accumulator tank, conduit means connecting said accumulator and compensating tanks and a manually con trolled valve in said conduit.

2. An equilibrator comprising a cylinder, a piston slidable in said cylinder and adapted to be connected to an unbalanced load to be equilibrated, an accumulator tank containing hydraulic fluid and charged with gas under pressure, conduit means connecting said accumulator tank and said cylinder on one side of said piston and means to compensate said equilibrator for ambient temperature changes comprising a compensating tank charged with gas to a pressure substantially equal to the average pressure in said accumulator tank; a conduit connecting said accumulator and compensatingtanks and a manually controlled valve in said conduit.

3. In combination with a gun having a support and barrel mechanism pivoted thereto for movement in elevation, an equilibrator comprising a slidably connected piston and cylinder connected between said support and barrel mechanism, an accumulator tank charged with gas under pressure connected'to said cylinder on one side of said piston, pressure responsive means connected to the top of the accumulator tank and calibrated to the elevation of the gun barrel, means to compensate said equilibrator for changes in ambient temperature comprising a compensating tank charged with gas to a pressure equal to the average pressure insaid accumulator tank, conduit means connecting said'accurnulator and compensating tanks, and means for regulating the pressure in the ac-v cumulator tankto the calibrated pressure for each gun barrel elevation, to maintain the gun barrel balanced for changes in ambient temperatures.

References Cited in the tile of this patent UNITED STATES PATENTS 1,464,680 Lassen Aug. 14, 1923 1,602,113 Joyce Oct. 5, 1926 1,938,956 Fee Dec. 12, 1933 2,754,725 Flem July 17, 1956, 2,857,815 Magnuson Oct. 28, 1958 2,946,263 Bruehl July 26, 1960; 

